(CNN) -- When Mark Shields started his job at the American Red Cross in Madison, Wisconsin, he rolled up his sleeve to give blood. It made sense. Part of his job was encouraging the public to donate and supporting the organization's lifesaving mission.
Before he could give, he was told that his blood could never be accepted. Because he's gay.
"I was 23 at the time. I was just coming out," he said. "I was trying to be part of our organization's mission and feeling like I can't do this. ... I certainly felt put on the spot. It was a bad feeling for a lot of reasons."
Under Food and Drug Administration rules, men who have had sex -- even once -- with another man since 1977 are not permitted to give blood. The rule was implemented in 1983, sparked by concerns that HIV, the virus that causes AIDS, was tainting the blood supply. Screening tests to identify HIV-positive blood had not been developed. The policy was seen as a safety measure.
Mark Shields promoted blood donations for two years at the American Red Cross.But today, with the availability of more accurate testing, activists, blood organizations and several U.S. senators say the lifetime ban is "medically and scientifically unwarranted" and are calling for change.
The Federal Advisory Committee on Blood Safety and Availability will consider the issue in meetings June 10 and 11 in Rockville, Maryland. The committee makes recommendations to the secretary of the Department of Health and Human Services, which oversees the FDA.
Medical opinions vary; some experts say that lifting the ban could pose health risks to blood recipients.